Fuel system



y 23, 1967 v M. F, HOMFELD ETAL 3,320,938

FUEL SYSTEM Filed Jan. 8, 1965 NIFOLD CUUM FUEL IN VENTORS HTTOR/VEV United States Patent 3,320,938 FUEL SYSTEM Max F. Homfeld', Royal Oak, and Stanley H. Mick, St.

Clair Shores, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Jan. 8, 1965, Ser. No. 424,354 7 Claims. (Cl. 123-139) This invention relates to a fuel system incorporating improved components and advantageously combining a shuttle piston type injection fuel distributor with an air mass flow fuel metering control.

It is generally accepted opinion that fuel injection offers distinct advantages over carburetion as a method of supplying a charge of fuel and air to the combustion cham bers of an internal combustion engine. Among these advantages: engine performance may be increased because the intake manifold design is not limited by the requirement that it carry vaporized fuel, and fuel economy is in creased due to the decreased variation in cylinder-to-cylinder air-fuel ratios.

This invention provides a fuel injection system in which the fuel is maintained under pressure without requiring recirculation. The possibility of fuel vapor formation and the resultant problems of vapor lock and long cranking after a hot soak are thereby eliminated.

This invention also provides a fuel injection system in which fuel metering is controlled by an air valve in the air inlet which is positioned by a diaphragm and spring combination adapted to maintain a constant air pressure differential in the air inlet. Thus, the air valve is responsive to air flow throughout the range of engine operating conditions and sufficient force is available to provide proper fuel metering. The problem of insufiicient control over fuel metering during engine idling is thus eliminated. Fuel metering is accomplished by varying the area of a metering orifice with a contoured rod controlled from the air valve.

This invention further provides a timed fuel injection system in which these air and fuel metering controls are combined with an injection fuel distributor incorporating a shuttle piston and a rotor cooperating to distribute the fuel to the injection nozzles. The fuel distributor has a stroke control piston to control the stroke of the shuttle piston and thus maintain a constant fuel pressure differential across the fuel metering orifices to obtain precise fuel metering. In this arrangement, source fuel pressure and metered fuel pressure are applied against the stroke control piston so that the quantity of fuel supplied to the cylinders increases as the fuel pressure differential across the fuel metering orifices decreases, thereby tending to restore the fuel pressure differential to a predetermined value. The stroke control piston also has an accumulatin g effect which allows a non-pulsating flow of fuel through the fuel metering orifices and increases the accuracy of the metering control. p

This invention additionally provides a fuel injection system incorporating a compensation piston controlled coincidentally with the throttle valve to provide enrichment of the charge of fuel and air upon engine acceleration. The compensation piston increases the pressure of the metered fuel and the stroke control piston is forced to permit a longer stroke of the shuttle piston. An unmetered quantity of fuel is then distributed to the cylinders to provide an enriched mixture for acceleration.

Also included in this fuel system is a choke adapted to enrich the charge of fuel and air during cold engine operation. The choke valve provides a false signal to the air valve and is controlling diaphragm, causing the air valve to open wider during cold engine operation than during normal engine operation for any given air mass flow, whereby the contoured rod is withdrawn from the metering orifice to permit increased fuel flow to the cylinders.

The details and other objects and advantages of this invention are disclosed in the following description and in the drawing, in which:

FIGURE 1 is an elevation view, partly in section, of the air intake, the intake manifold, and a cylinder of an internal combustion engine; and

FIGURE 2 is a sectional plan view of the fuel metering control and the fuel distributor.

Referring to the drawing, air is supplied through an air inlet 10 and an intake manifold 12 to the: cylinders 14 of an internal combustion engine. The amount of air supplied to the engine is controlled by the engine operator through a throttle valve 16 rotatably mounted in inlet 10. The air flow through inlet 10 is measured by an air valve 13 rotat-ably mounted in inlet 10.

Air valve 18 is controlled by a. diaphragm 20 which has air pressure in inlet 10 upstream of air valve 18 applied against one side through a tube 22 and which has air pressure in inlet 10 downstream of air valve 18 and upstream of throttle valve 16 applied against the other side..

These pressures act on diaphragm 20 in an air valve opening direction against the bias of a spring 24. Diaphragm 18 and spring 24 cooperate to maintain a. constant air pressure'differential across air valve 18. Thus, even during low air mass flow operating conditions such as at idle, sufficient force is avaialble to properly control fuel metering.

Air valve 18 is secured to a shaft 26 which extends through the side of inlet 10. A pair of contoured rods 30 and 32 is operatively connected to shaft 26 by lever arm 33. Rods 30 and 32 cooperate with metering orices 34 and 36, respectively, to vary the effective area thereof. Upon opening of air valve 18, rods 30 and 32 are withdrawn from orifices 34 and 36, allowing an increased quantity of fuel to pass therethrough.

Pressurized fuel is supplied to orifices 34 and 36 by a pump (not shown) through a conduit 38 to a housing in which the contoured rods 30 and 32 and their respective metering orifices 34 and 36 are located. Rod 30 and orifice 34 meter fuel for economy engine operation and are directly connected with conduit 38 through an annular chamber 42.

Rod 32 and orifice 36 meter fuel when power enrichment is required, such as during periods of low vacuum in intake manifold 12. As a control for orifice 36, manifold vacuum is applied through a conduit 44 against a' diaphragm 46 biased by a spring 48. A plunger 50 is connected to diaphragm 46. Another diaphragm 52 is connected to plunger 50 and seats across the end of a boss having a a conduit 54 extending through housing 40 to orifice 36, thereby preventing fuel flow from conduit 38 through annular chamber 42 to conduit 54.

During periods of low manifold vacuum, such as at wide open throttle or during engine acceleration, diaphragm 46 and thus plunger 50 and diaphragm 52 are biased away from conduit 54 by spring 43, and fuel may flow to orifice 36. Fuel is then metered through both orifices 34 and 36 and an enriched mixture is obtained for power operation. During periods of high manifold vacuum, such as at idle or during steady state engine operation, diaphragm 52 seals conduit 54 from annular chamber 42, whereby fuel is metered only through orifice 34..

After the fuel has been metered through orifices 34 and 36, it passes through a conduit 56 to the fuel distributor 58. Distributor 58 includes a rotor 60 driven through a shaft 62 by the engine. Rotor 69 cooperates with a stator 64, in which is formed a cylindrical cavity housing a shuttle piston 66, to distribute fuel to the various conduits 68 which lead to fuel injection nozzles 70 located in the intake manifold 12 adjacent the inlet valve 72 of each cylinder 14.

The operation of rotor 60 is such that fuel is supplied first to the chamber at one end of shuttle piston 66 through a passage 74 in the rotor and a passage 76 in the stator, and then to the chamber at the other end of shuttle piston 66 through passage 74 in the rotor and a passage 78 in the stator. As fuel is supplied to one end of shuttle piston 66, fuel is pumped from the other end of shuttle piston 66 and passes through passage 76 or 78 in the stator and groove 80 in the rotor to passages 92 in the stator which communicate with conduits 68. Thus, fuel is sequentially distributed to nozzles 70 by the cooperation of rotor 60 and shuttle piston 66.

A plunger 84 controls the length of the stroke of shuttle piston 66 and is biased by a spring 86 to permit relatively long strokes of shuttle piston 66. Plunger 84 abuts a stroke control piston 88 against one end of which fuel from the pump is applied and against the other end of which metered fuel is applied. Since a drop in fuel pressure occurs at the fuel passes through metering orifices 34 and 36, stroke control piston 88 is biased to permit relatively short strokes of shuttle piston 66. As rods 30 and 32 are retracted from orifices 34 and 36 and more fuel flows therethrough, the pressure of the metered fuel increases and stroke control piston 88 moves to the left permitting relatively long strokes of shuttle piston 66 to distribute the additional fuel to cylinders 14. In this manner the desired air fuel ratio is obtained for all engine speeds.

Stroke control piston 88 also has an accumulating effect to prevent pulsation in the fuel flow through the metering orifices 34 and 36. This accumulating effect permits fuel flow from housing 40 through a conduit 90, and thus permits steady flow through orifices 34 and 36.

The fuel injection system also includes means for providing enrichment during acceleration. A piston 92, operated through a level arrangement 94 coincidentally with throttle valve 16, is adapted to increase the pressure of the metered fuel and force stroke control piston 88 to permit relatively long strokes of shuttle piston 66. An unmetered quantity of fuel is thereby distributed by rotor 60 and shuttle piston 66 to nozzles 70 for acceleration enrichment.

A choke valve 96 is also located in inlet downstream of air valve 18. Choke valve 96 may be operated in the customary manner by an automatic control (not shown). The pressure differential measured by diaphragm 20 is measured across both air valve 18 and choke valve 96. During cold engine operating conditions choke valve 96 closes, increasing the air pressure in inlet 10 between air valve 18 and choke valve 96. However, diaphragm 20 measures the pressure differential across both air valves 18 and choke valve 96, and thus opens air valve 18 wider than it would be opened for the pressure drop across air valve 18 alone. This allows increased fuel flow through orifices 34 and 36. Thus, enrichment of the fuel and air charge is accomplished for cold engine operating conditions.

It will be appreciated from the foregoing that this invention provides a pressurized, non-recirculating fuel injection system wherein an air valve fuel metering control and a shuttle piston type fuel distributor are com bined in an advantageous manner. The additional features of a choke to control air valve position for cold enrichment, a manifold vacuum controlled fuel metering orifice for power enrichment, a stroke control piston to control the quantity of injected fuel, and a compensation piston to provide additional fuel for acceleration enrichment combine to enhance the efiiciency of this fuel injection system. It will be appreciated that many of these features may be advantageously incorporated in other types of fuel systems.

We claim:

1. A multiple cylinder internal combustion engine fuel injection system comprising an air inlet having an air valve to measure air flow, a pressurized fuel supply having orifice means to meter fuel flow and having metering rod means controlled by said air valve to variably restrict fuel fiow through said orifice means and having an outlet for fuel flow in a predetermined pressure range, and a fuel distributor including a stator and an engine driven rotor, said stator having a plurality of outlet passages to supply fuel to one of the engine cylinders at a predetermined pressure slightly lower than the pressure of said fuel supply outlet and having a cylindrical cavity, said fuel distributor further including a reciprocable shuttle piston dividing said cavity axially into two chambers, said stator additionally having two passages each extending to one of said chambers, passage means in said rotor to supply fuel from said fuel supply outlet to one of said chambers and to distribute the fuel from the other of said chambers to one of said outlets whereby said shuttle piston is reciprocated to pump fuel from said other chamber as fuel is supplied to said one chamber, said passage means being adapted upon rotation of said rotor to supply fuel to said chambers in sequence and to sequentially distribute fuel to each of said outlets.

2. The system of claim 1 wherein said orifice means comprises an economy orifice and a power orifice to meter fuel flow, and which further includes a throttle disposed in said air inlet downstream of said air valve to control air flow and means responsive to relatively low pressure in said air inlet downstream of said throttle to prevent fuel flow through said power orifice.

3. The system of claim 1 wherein said fuel distributor further includes a stroke control piston and plunger controlling the stroke of said shuttle piston, said stroke control piston having a portion biased by fuel pressure upstream of said orifice means to permit relatively short shuttle piston strokes and having a portion biased by fuel pressure downstream of said orifice means to permit relatively long shuttle piston strokes whereby said stroke control piston and plunger are biased to permit relatively short strokes of said shuttle piston, and spring means biasing said stroke control piston and plunger to permit relatively long strokes of said shuttle piston, said orifice means and said stroke control piston and plunger being adapted in combinaton to regulate the amount of fuel supplied by said fuel distributor to the engine cylinders.

4. The system of claim 3 which further includes a throttle in said air inlet to control air flow and means to temporarily increase the fuel pressure downstream of said metering means coincidentally with opening of said throttle whereby relative long shuttle piston strokes are permitted and unmetered accelerating fuel is supplied to the engine.

5. A multiple cylinder internal combustion engine fuel injection system comprising an air inlet, a throttle in said air inlet to control air flow, an air valve in said air inlet upstream of said throttle to control air flow, spring means exerting a closing force on said air valve, a pressure responsive diaphragm connected to said air valve, said diaphragm having air pressure in said air inlet upstream of said air valve applied against one side and having air pressure in said air inlet between said air valve and said throttle applied against the opposing side whereby an opening force is exerted on said air valve, a pressurized fuel supply having economy and power orifices to meter fuel flow, metering rods controlled by said air valve to variably restrict said orifices, means responsive to relatively low pressure in said air inlet downstream of said throttle to prevent fuel flow through said power orifice, a fuel distributor including a stator and an engine driven rotor, said stator having a plurality of outlets each adapted to supply fuel to one of the engine cylinders and having a cylindrical cavity, said fuel distributor further including a reciprocable shuttle piston dividing said cavity into two chambers, means in said rotor to supply fuel from said fuel supply to said chambers in sequence whereby said shuttle piston reciprocates to pump fuel from one chamber as fuel is supplied to the other chamber, and additional means in said rotor to distribute the fuel pumped during one stroke of said shuttle piston to one of said outlets and to sequentially distribute fuel to each of said outlets, said fuel distributor also including a plunger controlling the stroke of said shuttle piston, a spring biasing said plunger to permit relatively long shuttle piston strokes, a stroke control piston associated with said plunger, said stroke control piston having a portion biased by fuel pressure upstream of said orifices to permit relatively short shuttle piston strokes and having a portion biased by fuel pressure downstream of said orifices to permit relatively long shuttle piston strokes whereby said stroke control piston and plunger are biased to permit relatively short shuttle piston strokes, and a compensator piston operated coincidentally with opening of said throttle to temporarily increase the fuel pressure downstream of said orifices whereby relatively long shuttle piston strikes are permitted and unmetered accelerating fuel is supplied to the engine cylinders.

6. A system for sup-plying a mixture of fuel and air to an internal combustion engine comprising an air inlet, a throttle in said inlet to control air flow, a fuel inlet having economy and power orifices to meter fuel flow, said fuel inlet having an annular chamber connected to said economy orifice and including a boss extending partially into and concentric with said annular chamber, said boss having a concentric passage extending from said chamber to said power orifice, the end of said boss forming a valve seat surrounding said passage, a first flexible diaphragm extending across the end of said annular chamher and cooperating with said valve seat to separate said chamber from said passage and prevent fuel flow from said chamber through said passage, and a second flexible diaphragm connected to said first diaphragm and responsive to relatively high pressure in said air inlet downstream of said throttle to permit movement of said first diaphragm away from said valve seat to allow fuel flow from said chamber through said passage.

7. Means for supplying a mixture of fuel and air to an internal combustion engine comprising an air inlet, an air valve rotatably mounted in said air inlet to control air flow, a fuel inlet having means controlled by said air valve to increase fuel flow as said air valve opens to increase .air flow, a pressure responsive diaphragm connected to said air valve, said diaphragm having air pressure in said air inlet upstream of said air valve applied thereagainst in an air valve opening direction and having air pressure at a location in said air inlet downstream of said air valve applied thereagainst in an air valve closing direction whereby said air valve is biased in an air valve opening direction, spring means biasing said air valve in an air valve closing direction whereby a tendency to maintain constant pressure differential across said air valve is created, and a choke valve rotatably disposed in said air inlet intermediate said air valve and said air inlet location downstream of said air valve whereby the pressure at said location is decreased as said choke valve closes to cause said diaphragm to open said air valve and increase fuel flow.

References Cited by the Examiner UNITED STATES PATENTS 1,528,787 3/1925 Rayfield 261-501 X 2,126,709 8/ 1938 Alden.

2,447,268 8/1948 Evans 123-1 19 2,852,011 9/1958 Pringham 1231 19 2,876,758 3/1959 Armstrong 123-1l9 X 3,025,797 3/ 1962 Hutcheon.

MARK NEWMAN, Primary Examiner.

LAURENCE M, GOQDRIDGE, Examiner, 

1. A MULTIPLE CYLINDER INTERNAL COMBUSTION ENGINE FUEL INJECTION SYSTEM COMPRISING AN AIR INLET HAVING AN AIR VALVE TO MEASURE AIR FLOW, A PRESSURIZED FUEL SUPPLY HAVING ORIFICE MEANS TO METER FUEL FLOW AND HAVING METERING ROD MEANS CONTROLLED BY SAID AIR VALVE TO VARIABLY RESTRICT FUEL FLOW THROUGH SAID ORIFICE MEANS AND HAVING AN OUTLET FOR FUEL FLOW IN A PREDETERMINED PRESSURE RANGE, AND A FUEL DISTRIBUTOR INCLUDING A STATOR AND AN ENGINE DRIVEN ROTOR, SAID STATOR HAVING A PLURALITY OF OUTLET PASSAGES TO SUPPLY FUEL TO ONE OF THE ENGINE CYLINDERS AT A PREDETERMINED PRESSURE SLIGHTLY LOWER THAN THE PRESSURE OF SAID FUEL SUPPLY OUTLET AND HAVING A CYLINDRICAL CAVITY, SAID FUEL DISTRIBUTOR FURTHER INCLUDING A RECIPROCABLE SHUTTLE PISTON DIVIDING SAID CAVITY AXIALLY INTO TWO CHAMBERS, SAID STATOR ADDITIONALLY HAVING TWO PASSAGES EACH EXTENDING TO ONE OF SAID CHAMBERS, PASSAGE MEANS IN SAID ROTOR TO SUPPLY FUEL FROM SAID FUEL SUPPLY OUTLET TO ONE OF SAID CHAMBERS AND TO DISTRIBUTE THE FUEL FROM THE OTHER OF SAID CHAMBERS TO ONE OF SAID OUTLETS WHEREBY SAID SHUTTLE PISTON IS RECIPROCATED TO PUMP FUEL FROM SAID OTHER CHAMBER AS FUEL IS SUPPLIED TO SAID ONE CHAMBER, SAID PASSAGE MEANS BEING ADAPTED UPON ROTATION OF SAID ROTOR TO SUPPLY FUEL TO SAID CHAMBERS IN SEQUENCE AND TO SEQUENTIALLY DISTRIBUTE FUEL TO EACH OF SAID OUTLETS. 